Self-aligned shallow trench isolation and doping for vertical fin transistors

ABSTRACT

A method of forming a vertical fin field effect transistor (vertical finFET) with a self-aligned shallow trench isolation region, including forming a pinch-off layer on one or more vertical fin segments, wherein the pinch-off layer has a thickness on the sidewalls of the one or more vertical fin segments, forming a trench mask layer on predetermined portions of the pinch-off layer, removing portions of the pinch-off layer not covered by the trench mask layer, where the removed portions of the pinch-off layer exposes underlying portions of the substrate, and removing at least a portion of the substrate to form one or more isolation region trenches, where the distance of the sidewall of one of the one or more isolation region trenches to an adjacent vertical fin segment is determined by the thickness of the pinch-off layer.

BACKGROUND Technical Field

The present invention generally relates to self-aligned shallow trenchisolation regions and masking of doped substrate regions, and moreparticularly to an approach to control the alignment of mask layers withsemiconductor device features to reduce dimensional variations.

Description of the Related Art

A Field Effect Transistor (FET) typically has a source, a channel, and adrain, where current flows from the source to the drain, and a gate thatcontrols the flow of current through the channel. Field EffectTransistors (FETs) can have a variety of different structures, forexample, FETs have been fabricated with the source, channel, and drainformed in the substrate material itself, where the current flowshorizontally (i.e., in the plane of the substrate), and finFETs havebeen formed with the channel extending outward from the substrate, butwhere the current also flows horizontally from a source to a drain. Thechannel for the finFET can be an upright slab of thin rectangular Si,commonly referred to as the fin with a gate on the fin, as compared to aMOSFET with a single gate in the plane of the substrate. Depending onthe doping of the source and drain, an n-FET or a p-FET may be formed.

Examples of FETs can include a metal-oxide-semiconductor field effecttransistor (MOSFET) and an insulated-gate field-effect transistor(IGFET). Two FETs also may be coupled to form a complementary metaloxide semiconductor (CMOS), where a p-channel MOSFET and n-channelMOSFET are coupled together.

With ever decreasing device dimensions, forming the individualcomponents and electrical contacts become more difficult. An approach istherefore needed that retains the positive aspects of traditional FETstructures, while overcoming the scaling issues created by formingsmaller device components.

SUMMARY

In accordance with an embodiment of the present principles, a method isprovided for forming a vertical fin field effect transistor (verticalfinFET) with a self-aligned shallow trench isolation region. The methodincludes forming a pinch-off layer on one or more vertical fin segments,wherein the pinch-off layer has a thickness on the sidewalls of the oneor more vertical fin segments. The method further includes the steps offorming a trench mask layer on predetermined portions of the pinch-offlayer, and removing portions of the pinch-off layer not covered by thetrench mask layer, where the removed portions of the pinch-off layerexposes underlying portions of the substrate. The method furtherincludes the step of removing at least a portion of a substrate to formone or more isolation region trenches, where the distance of thesidewall of one of the one or more isolation region trenches to anadjacent vertical fin segment is determined by the thickness of thepinch-off layer.

In accordance with an embodiment of the present principles, a method isprovided for forming a vertical fin field effect transistor (verticalfinFET) with a self-aligned shallow trench isolation region. The methodincludes forming one or more vertical fins by a sidewall image transferprocess, and forming a pinch-off layer on one or more vertical finsegments, wherein the pinch-off layer has a thickness on the sidewallsof the one or more vertical fin segments. The method further includesthe steps of forming a trench mask layer on predetermined portions ofthe pinch-off layer, and removing portions of the pinch-off layer notcovered by the trench mask layer, where the removed portions of thepinch-off layer exposes underlying portions of the substrate. The methodfurther includes the step of removing at least a portion of thesubstrate to form one or more isolation region trenches, where thedistance of the sidewall of one of the one or more isolation regiontrenches to an adjacent vertical fin segment is determined by thethickness of the pinch-off layer.

In accordance with an embodiment of the present principles, asemiconductor device structure is provided. The semiconductor devicestructure includes a plurality of vertical fin segments on a substrateseparated by one or more fin gaps and/or one or more fin trenches. Thesemiconductor device structure further includes a pinch-off layercovering the plurality of vertical fin segments and at least a portionof the surface of the substrate in the one or more fin gaps and/or oneor more fin trenches, and one or more trench mask blocks in at least aportion of at least one of the one or more fin gaps or at least one ofthe one or more fin trenches; where the one or more trench mask blockscovers at least a portion of the pinch-off layer in the one or more fingaps and/or one or more fin trenches.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 shows a cross-sectional side view of a substrate, in accordancewith an embodiment of the present principles;

FIG. 2 shows a cross-sectional side view of a hardmask layer and a linerlayer, on a substrate, in accordance with an embodiment of the presentprinciples;

FIG. 3 shows a cross-sectional side view of a sacrificial mandrel layeron the hardmask layer and liner layer, on a substrate, in accordancewith an embodiment of the present principles;

FIG. 4 shows a cross-sectional side view of a photo-mask layer on thesacrificial mandrel layer and hardmask layer, in accordance with anembodiment of the present principles;

FIG. 5 shows a cross-sectional side view of a photo-mask block on eachof a plurality of sacrificial mandrels on the hardmask layer, inaccordance with an embodiment of the present principles;

FIG. 6 shows a cross-sectional side view of a plurality of sacrificialmandrels on the hardmask layer after removal of the photo-mask blocks,in accordance with an embodiment of the present principles

FIG. 7 shows a cross-sectional side view of a spacer layer on theplurality of sacrificial mandrels, in accordance with an embodiment ofthe present principles;

FIG. 8 shows a cross-sectional side view of a plurality of spacers onopposing sides of the plurality of sacrificial mandrels, in accordancewith an embodiment of the present principles;

FIG. 9 shows a cross-sectional side view of a plurality of free-standingspacers after removal of the sacrificial mandrels, in accordance with anembodiment of the present principles;

FIG. 10 shows a cross-sectional side view of a plurality offree-standing spacers on a plurality of hardmask fin templates, inaccordance with an embodiment of the present principles;

FIG. 11 shows a cross-sectional side view of a plurality of spacers andhardmask fin templates on a plurality of fins formed in the substrate,in accordance with an embodiment of the present principles;

FIG. 12 shows a cross-sectional side view of a plurality of hardmask fintemplates and template liners on a plurality of fins formed in thesubstrate after removal of the spacers, in accordance with an embodimentof the present principles;

FIG. 13 shows a cross-sectional side view of a filler layer covering theplurality of hardmask fin templates and vertical fins on the substrate,in accordance with an embodiment of the present principles;

FIG. 14 shows a cross-sectional side view of a filler layer and hardmaskfin templates having a flat top surface, in accordance with anembodiment of the present principles;

FIG. 15 shows a cross-sectional side view of a patterned fin-cut masklayer on the flat surface of the filler layer and hardmask fintemplates, in accordance with an embodiment of the present principles;

FIG. 16 shows a cross-sectional perspective view of a patterned fin-cutmask layer on the flat surface of the filler layer and hardmask fintemplates, in accordance with an embodiment of the present principles;

FIG. 17 shows a cross-sectional side view of a patterned fin-cut masklayer on the flat surface of the filler layer and hardmask fin templateswith predetermined hardmask fin templates removed, in accordance with anembodiment of the present principles;

FIG. 18 shows a cross-sectional side view of the long axis of apatterned fin-cut mask layer on the hardmask fin templates, templateliners, and vertical fins, with intervening fin trenches, in accordancewith an embodiment of the present principles;

FIG. 19 shows a cross-sectional perspective view of patterned and etchedfiller layer, hardmask fin templates, template liners, and verticalfins, with intervening fin trenches and fin-gaps, in accordance with anembodiment of the present principles;

FIG. 20 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentswith intervening fin-gaps after removal of the protective liner and/orfiller layer blocks, in accordance with an embodiment of the presentprinciples;

FIG. 21 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentscovered by a pinch-off layer, in accordance with an embodiment of thepresent principles;

FIG. 22 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, with a pinch-off layer, in accordance with an embodiment ofthe present principles;

FIG. 23 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentscovered by a trench mask layer, in accordance with an embodiment of thepresent principles;

FIG. 24 shows a cross-sectional perspective view of patterned and etchedtrench mask in a fin-gap and fin trench between filler layer blocks, inaccordance with an embodiment of the present principles;

FIG. 25 shows a partial cross-section and side view of the long axis ofvertical fin segments of FIG. 24 showing a plurality of trench maskblocks in fin trenches and fin-gaps, in accordance with an embodiment ofthe present principles;

FIG. 26 shows a side view of a plurality of trench mask openingsextending along the fin-gaps and trench mask blocks in the fin trenchbehind the pinch-off layer covered vertical fin segments, in accordancewith an embodiment of the present principles;

FIG. 27 shows a partial cross-section and side view of the long axis ofvertical fin segments of FIG. 24 showing an isolation region trenchextending into the substrate, and trench mask blocks shown in a fin gapbehind the pinch-off layer covered vertical fin segments, in accordancewith an embodiment of the present principles;

FIG. 28 shows a cross-sectional side view of a plurality of isolationregion trenches extending into the substrate between adjacent hardmaskfin template segments, template liner segments, and vertical finsegments, in accordance with an embodiment of the present principles;

FIG. 29 shows a cross-sectional side view of a plurality of isolationregion trenches extending into the substrate between adjacent hardmaskfin template segments, template liner segments, and vertical finsegments, in accordance with an embodiment of the present principles;

FIG. 30 shows a cross-sectional side view of hardmask fin templatesegments, template liner segments, and vertical fin segments, with adielectric fill layer in the trench mask openings and isolation regiontrenches, in accordance with an embodiment of the present principles;

FIG. 31 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, with a dielectric fill layer in the trench mask openings andisolation region trenches, in accordance with an embodiment of thepresent principles;

FIG. 32 shows a cross-sectional side view of a plurality offree-standing hardmask fin template segments, template liner segments,and vertical fin segments, after removal of the pinch-off layer and aportion of the dielectric fill layer, in accordance with an embodimentof the present principles;

FIG. 33 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, after removal of the pinch-off layer and a portion of thedielectric fill layer, in accordance with an embodiment of the presentprinciples; and

FIG. 34 shows a cross-sectional side view of a plurality offree-standing vertical fin segments, and self-aligned shallow trenchisolation regions, in accordance with an embodiment of the presentprinciples.

DETAILED DESCRIPTION

Principles and embodiments of the present disclosure relate generally tocontrolling feature locations, dimensions, and inter-feature pitch byreducing or avoiding variations in feature placement due to themisalignment of mask layers. Self-alignment is typically a process inwhich control of the placement/formation of device features/componentsis not limited by the tolerance of control on the positioning of alithography mask. A device component (e.g., a spacer) or feature (e.g.,doped region) may be located through control of component widths and/orlayer thicknesses, or avoidance of sequential mask positionings that mayintroduce cumulative placement errors. One or more device features may,thereby, be self-aligned with other device features through the use ofalready defined feature dimensions and locations.

For each lithography step, a lithography mask must be aligned withfeatures already present on a substrate, and the location of futurefabricated features may also be taken into account. The continuedreduction in feature sizes has made this alignment more and moredifficult. Two such features implemented in the construction of verticalfin field effect transistors (vertical finFETs) is the doped region inthe substrate, that may form a bottom source/drain, and a shallow trenchisolation (STI) region that may be formed in the substrate toelectrically separate two neighboring devices. A problem that can ariseis the ability to align a lithography mask with one or more fins alreadypatterned and formed on the substrate. Misalignment of the lithographymask can result in the misplacement of a masked area or an opening in amask layer after patterning and development. Features present on thesubstrate, therefore, may not be sufficiently covered by a protectivemasking layer, and/or an opening in the mask layer may be located in anunacceptable position resulting in the incorrect placement of asubsequent feature, for example, a trench for an STI. Subsequentetchings or depositions may create device features that are too closetogether, too far apart, not sufficiently overlapping, or interfering,for example, due to excessive overlap.

In one or more embodiments, an opening in a mask may be suitably alignedwith the location of existing fins on a substrate to allow formation ofa bottom source/drain below the fins through an ion implantationprocess. A doped bottom plate may be formed in a region of the substratethat overlaps the position of the existing fins on the substrate.Alignment of the mask may be controlled by relying on the thickness of alayer on the vertical surfaces of adjacent device features to define thelocation of an opening and subsequent etching and/or depositions.

In one or more embodiments, a hardmask layer may be formed on thesurfaces perpendicular to the substrate surface by a conformaldeposition that allows accurate control of the hardmask layer thicknesson both the vertical surfaces and the substrate surface. Control of thelayer thickness on the vertical surfaces can provide controlleddisplacement of an opening from the vertical surface by a lateraldistance equal to the thickness. In various embodiments, the thicknessof a conformally deposited hardmask layer may be sufficient to fill thespace between two adjacent vertical fins, and thereby pinch off theregion between the fins.

Exemplary applications/uses to which the present principles can beapplied include, but are not limited to: formation of vertical finFETs,complementary metal oxide silicon (CMOS) field effect transistors (FETs)formed by coupled finFETs, and digital gate devices (e.g., NAND, NOR,XOR, etc.).

In various embodiments, the materials and layers may be deposited byphysical vapor deposition (PVD), chemical vapor deposition (CVD), atomiclayer deposition (ALD), molecular beam epitaxy (MBE), or any of thevarious modifications thereof, for example plasma-enhanced chemicalvapor deposition (PECVD), metal-organic chemical vapor deposition(MOCVD), low pressure chemical vapor deposition (LPCVD), electron-beamphysical vapor deposition (EB-PVD), and plasma-enhanced atomic layerdeposition (PE-ALD). The depositions may be epitaxial processes, and thedeposited material may be crystalline. In various embodiments, formationof a layer may be by one or more deposition processes, where, forexample, a conformal layer may be formed by a first process (e.g., ALD,PE-ALD, etc.) and a fill may be formed by a second process (e.g., CVD,electrodeposition, PVD, etc.).

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, shows a cross-sectionalside view of a substrate in accordance with an exemplary embodiment.

In one or more embodiments, a substrate 110 may be a semiconductor or aninsulator with an active surface semiconductor layer. At least a portionof the substrate may be crystalline, semi-crystalline, microcrystalline,or amorphous. The substrate may be essentially (i.e., except forcontaminants) a single element (e.g., silicon), primarily (i.e., withdoping) of a single element, for example, silicon (Si) or germanium(Ge), or the substrate may include a compound, for example, Al₂O₃, SiO₂,GaAs, SiC, or SiGe. The substrate may also have multiple materiallayers, for example, a semiconductor-on-insulator substrate (SeOI), asilicon-on-insulator substrate (SOI), germanium-on-insulator substrate(GeOI), or silicon-germanium-on-insulator substrate (SGOI). Thesubstrate may also have other layers forming the substrate, includinghigh-k oxides and/or nitrides. In one or more embodiments, the substrate110 may be a silicon wafer. In an embodiment, the substrate may be asingle crystal silicon (Si), silicon germanium (SiGe), or III-Vsemiconductor (e.g., GaAs) wafer, or have a single crystal silicon (Si),silicon germanium (SiGe), or III-V semiconductor (e.g., GaAs)surface/active layer.

In various embodiments, a sidewall image transfer (SIT) technique may beused to form one or more vertical fins 111 on the substrate. In atypical SIT process, spacers are formed on the sidewall of a sacrificialmandrel. The sacrificial mandrel is removed and the remaining uprightspacers are used to pattern the hardmask fin template(s) 121. Thehardmask fin template(s) 121 are used as a mask during the etch of a topportion of a semiconductor layer to form one or more vertical fins 111.The upright spacers are then removed after the semiconductor verticalfins 111 have been formed. In various embodiments, the substrate may bea single crystal Si substrate and the vertical fins may be singlecrystal silicon.

FIG. 2 shows a cross-sectional side view of a hardmask layer and a linerlayer, on a substrate, in accordance with an embodiment of the presentprinciples.

In one or more embodiments, a thin liner layer 120 may be formed on atleast a portion of the substrate 110. A hardmask layer 130 may be formedon at least a portion of the liner layer 120. In one or moreembodiments, the liner layer 120 and hardmask layer 130 may form one ormore fin templates.

In one or more embodiments, the thin liner layer 120 may have athickness in the range of about 1 nm to about 10 nm, or in the range ofabout 2 nm to about 5 nm.

In various embodiments, liner layer 120 may be an oxide, for example,silicon oxide (SiO), silicon oxynitride (SiON), or a combinationthereof. The liner layer 120 may protect the underlying substratematerial from having defects introduced by a silicon nitride deposition.

In one or more embodiments, the hardmask layer 130 may have a thicknessin the range of about 20 nm to about 100 nm, or in the range of about 35nm to about 75 nm, or in the range of about 45 nm to about 55 nm.

In various embodiments, hardmask layer 130 may be a nitride, forexample, silicon nitride (SiN), silicon oxynitride (SiON), or acombination thereof. In various embodiments, the liner layer 120 is adifferent material than the hardmask layer 130, such that the linerlayer 120 may act as an etch stop layer.

FIG. 3 shows a cross-sectional side view of a sacrificial mandrel layeron the hardmask layer and liner layer, on a substrate, in accordancewith an embodiment of the present principles.

In one or more embodiments, a sacrificial mandrel layer 140 may beformed on at least a portion of the hardmask layer 130. The sacrificialmandrel layer 140 may be a semiconductor material, for example,amorphous silicon (a-Si), polycrystalline silicon (p-Si),microcrystalline silicon (m-Si), amorphous carbon (a-C), or combinationsthereof.

FIG. 4 shows a cross-sectional side view of a photo-mask layer on thesacrificial mandrel layer and hardmask layer, in accordance with anembodiment of the present principles.

In one or more embodiments, a photo-mask layer 150 may be formed on atleast a portion of the sacrificial mandrel layer 140, where thephoto-mask layer 150 may be a soft mask, for example, poly methylmethacrylate (PMMA), that may be patterned and developed to formopening(s) and mask feature(s). In various embodiments, the photo-masklayer 150 may be patterned and developed to form one or more photo-maskblocks 151, that cover a portion of the sacrificial mandrel layer 140,while exposing portions of the sacrificial mandrel layer 140.

FIG. 5 shows a cross-sectional side view of a photo-mask block on eachof a plurality of sacrificial mandrels on the hardmask layer, inaccordance with an embodiment of the present principles.

In one or more embodiments, a plurality of sacrificial mandrels 141 maybe formed from the sacrificial mandrel layer 140, where an anisotropicetch may be used to form the sacrificial mandrels 141. An anisotropicetch may be a dry plasma etch, for example, a reactive ion etch (RIE),that preferentially removes material from the sacrificial mandrel layer140 in a direction normal to the surface, while limiting etching of thesidewalls. The plurality of sacrificial mandrels 141 may act astemplates for forming spacers.

In one or more embodiments, the sacrificial mandrels 141 may have awidth in the range of about 5 nm to about 60 nm, or in the range ofabout 10 nm to about 40 nm.

In one or more embodiments, the plurality of sacrificial mandrels 141may have a pitch between adjacent sacrificial mandrels 141. The pitchbetween adjacent sacrificial mandrels 141 may be in the range of about20 nm to about 200 nm, or in the range of about 70 nm to about 120 nm,or in the range of about 24 nm to about 80 nm, or in the range of about35 nm to about 100 nm.

FIG. 6 shows a cross-sectional side view of a plurality of sacrificialmandrels on the hardmask layer after removal of the photo-mask blocks,in accordance with an embodiment of the present principles.

In one or more embodiments, the photo-mask blocks 151 may be removedfrom each of sacrificial mandrels 141 by a suitable method (e.g.,ashing, dissolving, etc.), as would be known in the art. Removal of thephoto-mask blocks 151 may expose the top surface of the sacrificialmandrels 141.

FIG. 7 shows a cross-sectional side view of a spacer layer on theplurality of sacrificial mandrels, in accordance with an embodiment ofthe present principles.

In one or more embodiments, a spacer layer 160 may be formed on one ormore of the sacrificial mandrels 141. The spacer layer 160 may be formedby a blanket deposition over the sacrificial mandrels 141 and exposedportions of the surface of the hardmask layer 130, where the blanketdeposition may be a conformal deposition, for example by ALD, CVD, or acombination thereof.

In one or more embodiments, the spacer layer 160 may be an oxide, forexample, silicon oxide (SiO). The spacer layer 160 may be a differentmaterial than the hardmask layer 130, such that the hardmask layer 130acts as an etch stop.

In one or more embodiments, the spacer layer 160 may have a thickness inthe range of about 3 nm to about 25 nm, or in the range of about 5 nm toabout 20 nm, where the thickness of the spacer layer 160 may determinethe width of the spacers and fin templates, and ultimately the width ofthe fins.

FIG. 8 shows a cross-sectional side view of a plurality of spacers onopposing sides of the plurality of sacrificial mandrels, in accordancewith an embodiment of the present principles.

In one or more embodiments, a portion of the spacer layer 160 on thesurface of the hardmask layer 130 between the sacrificial mandrels 141,and portions of the spacer layer 160 on the top surface of thesacrificial mandrels 141, may be removed to form spacers 161. Portionsof the hardmask layer 130 may be exposed by removal of portions of thespacer layer 160. In various embodiments, portions of the spacer layer160 may be removed by etching in a manner that reduces the height of thespacer layer 160 (e.g., an etch-back) on the sidewalls of thesacrificial mandrels 141, and exposes the top surface of the sacrificialmandrels.

FIG. 9 shows a cross-sectional side view of a plurality of free-standingspacers after removal of the sacrificial mandrels, in accordance with anembodiment of the present principles.

In one or more embodiments, the sacrificial mandrels 141 may be removedto form a plurality of free-standing spacers 161, where the spacers mayhave a first pitch, P₁, controlled by the width of the sacrificialmandrels 141, and a second pitch, P₂, controlled by the pitch of thesacrificial mandrels 141. The sacrificial mandrels 141 may be removed bya selective isotropic etch that removes the material of the sacrificialmandrels 141 without notably effecting the spacers 161 or hardmask layer130.

In various embodiments, the pattern of the spacers 161 may betransferred to the hardmask layer 130.

FIG. 10 shows a cross-sectional side view of a plurality offree-standing spacers on a plurality of hardmask fin templates, inaccordance with an embodiment of the present principles.

In one or more embodiments, portions of the hardmask layer 130 betweenthe free-standing spacers 161 may be removed by a directional etch toform a plurality of hardmask fin templates 131.

In various embodiments, portions of the liner layer 120 between thehardmask fin templates 131 may be removed by a directional etch to formtemplate liners 121, and expose at least portions of the surface of thesubstrate. In various embodiments, portions of the hardmask layer 130and/or liner layer 120 may be removed by RIE.

FIG. 11 shows a cross-sectional side view of a plurality of spacers andhardmask fin templates on a plurality of fins formed in the substrate,in accordance with an embodiment of the present principles.

In one or more embodiments, one or more fin(s) 111 may be formed in thesubstrate 110 using the spacers 161 and/or hardmask fin templates 131.In various embodiments, the spacers 161 may be removed prior toformation of the fins 111, and the hardmask fin templates 131 may beused to mask the substrate 110. In various embodiments, the spacers 161may be removed after the formation of the fins 111.

FIG. 12 shows a cross-sectional side view of a plurality of hardmask fintemplates on a plurality of fins formed in the substrate after removalof the spacers, in accordance with an embodiment of the presentprinciples.

In one or more embodiments, the spacers 161 may be selectively removedto expose the top surface of the hardmask fin templates 131.

FIG. 13 shows a cross-sectional side view of a filler layer covering theplurality of hardmask fin templates and vertical fins on the substrate,in accordance with an embodiment of the present principles.

In one or more embodiments, a filler layer 170 may be formed on the oneor more hardmask fin templates 131, template liners 121, and verticalfins 111. The filler layer 170 may fill in the gaps between each of thehardmask fin templates 131, template liners 121, and vertical fins 111and extend above the top surface of the hardmask fin templates 131,where the filler layer 170 may be conformally deposited, for example, byALD and/or CVD.

In various embodiments, a protective liner 175 may be formed on thehardmask fin templates 131, template liners 121, and vertical fins 111before formation of the filler layer 170, where the protective liner 175may be a silicon nitride (e.g., Si₃N₄) conformally deposited on theexposed surfaces of the hardmask fin templates 131, template liners 121,and vertical fins 111. The protective liner 175 may protect the fin(s)from damage during formation of the filler layer 170 and/or subsequentprocessing steps.

FIG. 14 shows a cross-sectional side view of a filler layer and hardmaskfin templates having a flat top surface, in accordance with anembodiment of the present principles.

In one or more embodiments, a chemical-mechanical polishing (CMP) may beused to remove filler layer material above the top surface of thehardmask fin templates 131, and reduce the height of the filler layer170 to form a flat, uniform surface with the top surface of the hardmaskfin templates 131. The filler layer 170 may provide mechanical supportto the hardmask fin templates 131, template liners 121, and verticalfins 111 during chemical-mechanical polishing, and provide a uniformsurface for formation of a subsequent fin-cut mask layer.

FIG. 15 shows a cross-sectional side view of a patterned fin-cut masklayer on the flat surface of the filler layer and hardmask fintemplates, in accordance with an embodiment of the present principles.

In one or more embodiments, a fin-cut mask layer may be formed on atleast a portion of the surface of the filler layer 170 and hardmask fintemplates 131, and patterned and developed to form fin-cut mask blocks181, where the fin-cut mask blocks 181 cover selected hardmask fintemplates 131, while leaving one or more predetermined hardmask fintemplates 131 exposed.

In various embodiments, the fin-cut mask blocks 181 do not have toprecisely cover portions of the flat surface with the selected hardmaskfin templates 131. The positioning of the fin-cut mask blocks 181 canhave a tolerance equal to or less than the distance of the first pitch,P₁, and/or the second pitch, P₂, (e.g., whichever is smaller), as longas the fin-cut mask block 181 covers the particular hardmask fintemplates 131 that are to remain. The fin-cut mask blocks 181 are adifferent material than the hardmask fin templates 131 and filler layer170, so the in-cut mask blocks are not etched during removal of theselected hardmask fin templates and filler layer. In variousembodiments, the fin-cut mask layer and fin-cut mask blocks 181 may bean organic lithography material that may allow etching of both an oxidefiller layer and a nitride fin template at the same time, as would beknown in the art. In various embodiments, the fin-cut mask layer mayinclude two or more different layers.

FIG. 16 shows a cross-sectional perspective view of a patterned fin-cutmask layer on the flat surface of the filler layer and hardmask fintemplates, in accordance with an embodiment of the present principles.

In one or more embodiments, the fin-cut mask blocks 181 may be arrangedin a 2-dimensional pattern on the surface of the filler layer 170 andhardmask fin templates 131 to expose portions of the filler layer 170and hardmask fin templates 131 that will be removed to form fin-cuttrenches and fin-gaps.

FIG. 17 shows a cross-sectional side view of a patterned fin-cut masklayer on the flat surface of the filler layer and hardmask fin templateswith predetermined hardmask fin templates and vertical fins removed, inaccordance with an embodiment of the present principles.

In one or more embodiments, the predetermined hardmask fin templates 131exposed by the fin-cut mask blocks 181 may be removed, as well as aportion of the surrounding filler layer 170. The predetermined hardmaskfin templates 131 may be removed by RIE to form one or more fin-gaps190, where a fin-gap 190 may extend along the entire length of ahardmask fin template 131, template liner 121, and vertical fin 111, orinclude only a portion of the hardmask fin template 131, template liner121, and vertical fin 111. One or more hardmask fin templates 131,template liners 121, and vertical fins 111 may be removed down to thelevel of the substrate 110 to form a fin-gap 190. The width of thefin-gap 190 may depend on the number of hardmask fin templates 131,template liners 121, and vertical fins 111, removed, and the pitchbetween the hardmask fin templates 131, template liners 121, andvertical fins 111.

In various embodiments, the remaining hardmask fin templates 131,template liners 121, and vertical fins 111 may form a plurality ofdevices (e.g., vertical finFETs) having single or multiple fins, whereone or more vertical fins 111 may form a channel of a vertical finFET.In various embodiments, a vertical finFET may include multiple fins.

FIG. 18 shows a cross-sectional side view of the long axis of apatterned fin-cut mask layer on the hardmask fin templates, templateliners, and vertical fins, with intervening fin trenches, in accordancewith an embodiment of the present principles.

In one or more embodiments, one or more intervening fin trench(es) 200may be formed to separate one or more hardmask fin template(s) 131,template liner(s) 121, and vertical fin(s) 111 into two or more hardmaskfin template segments 135, template liner segments 125, and vertical finsegments 115. The separate stacks of hardmask fin template segments 135,template liner segments 125, and vertical fin segments 115 may have thesame length or different lengths depending on the size and arrangementof the fin-cut mask blocks 181, and the distances between fin-cut maskblocks 181.

FIG. 19 shows a cross-sectional perspective view of patterned and etchedfiller layer blocks, hardmask fin templates, template liners, andvertical fins, with intervening fin trenches and fin-gaps, in accordancewith an embodiment of the present principles.

In one or more embodiments, the filler layer 170 is divided into aplurality of filler layer blocks 171, and the hardmask fin template(s)131, template liner(s) 121, and vertical fin(s) 111 are divided into twoor more hardmask fin template segments 135, template liner segments 125,and vertical fin segments 115 by the intersecting fin trench(es) 200 andfin-gap(s) 190. In various embodiments, the fin trench(es) 200 may beapproximately perpendicular (e.g., ±5°, ±3°) to the fin-gap(s) 190,where the fin gaps 190 align approximately with the location of one ormore vertical fin(s) 111. The fin trench(es) 200 and fin-gap(s) 190 mayextend down to the level at which the vertical fin segments 115 meet thesubstrate surface 105.

The fin-gap(s) 190 may be formed by removing one or more adjacenthardmask fin template(s) 131, template liner(s) 121, and vertical fin(s)111. The fin trench(es) 200 may be formed by removing a portion of oneor more hardmask fin template(s) 131, template liner(s) 121, andvertical fin(s) 111 across the long direction to form a column of two ormore hardmask fin template segments 135, template liner segments 125,and vertical fin segments 115.

FIG. 20 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentswith intervening fin-gaps after removal of the protective liner and/orfiller layer blocks, in accordance with an embodiment of the presentprinciples.

In various embodiments, the filler layer blocks 171 may be removed toexpose the substrate surface 105, hardmask fin template segments 135,template liner segments 125, and vertical fin segments 115. Inembodiments having a protective liner 175 between the filler layerblocks 171 and hardmask fin template segments 135, template linersegments 125, and vertical fin segments 115, the protective liner 175may also be removed. The filler layer blocks 171 and protective liner175 may be removed by separate etching processes selective for thematerial of the filler layer blocks 171 and protective liner 175.

FIG. 21 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentscovered by a pinch-off layer, in accordance with an embodiment of thepresent principles.

In one or more embodiments, a pinch-off layer 210 may be formed on thehardmask fin template segments 135, template liner segments 125, andvertical fin segments 115. In various embodiments, the pinch-off layer210 may be conformally deposited on the sidewalls and/or endwalls of thehardmask fin template segments 135, template liner segments 125, andvertical fin segments 115.

In various embodiments, the pinch-off layer 210 may fill in the spacebetween the adjacent hardmask fin template segments 135, template linersegments 125, and vertical fin segments 115, while leaving an openingbetween hardmask fin template segments 135, template liner segments 125,and vertical fin segments 115 on opposite sides of a fin-gap 190. Thepinch-off layer 210 may be formed on portions of the substrate surface105 in the fin-gap 190.

In various embodiments, the pinch-off layer 210 may have a thickness inthe range of about 0.1 nm to about 25 nm, or in the range of about 1 nmto about 20 nm, or in the range of about 3 nm to about 10 nm, or in therange of about 5 nm to about 25 nm, or in the range of about 10 nm toabout 20 nm. The pinch-off layer 210 may be formed by atomic layerdeposition (ALD), where the thickness of the pinch-off layer 210 may becontrolled to a thickness of one monolayer of the material beingdeposited. In various embodiments, the pinch-off layer 210 may include,but not be limited to, SiO₂, SiN, SiON, or TiN. The pinch-off layer maybe a conformal layer deposited by ALD.

FIG. 22 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, with a pinch-off layer, in accordance with an embodiment ofthe present principles.

In various embodiments, the pinch-off layer 210 may cover portions ofthe substrate surface 105 exposed in the fin trench(es) 200 betweenhardmask fin template segments 135, template liner segments 125, andvertical fin segments 115.

FIG. 23 shows a cross-sectional side view of a plurality of hardmask fintemplate segments, template liner segments, and vertical fin segmentscovered by a trench mask layer, in accordance with an embodiment of thepresent principles.

In one or more embodiments, a trench mask layer 220 may be formed on atleast selective portions of the pinch-off layer 210, where the trenchmask layer 220 may fill in one or more fin trench(es) 200 and/orfin-gap(s) 190. The trench mask layer 220 may extend above the topsurface(s) of the pinch-off layer 210 on the hardmask fin templatesegments 135. The trench mask layer 220 may cover portions of thepinch-off layer 210 on the substrate surface 105.

In various embodiments, the trench mask layer 220 may be an organiclithography material, as would be known in the art, for example, anorganic planarization layer, that may allow etching of both an oxide anda nitride at the same time. In various embodiments, the trench masklayer 220 may be formed on the pinch-off layer 210 and in the one ormore fin trench(es) 200 and/or fin-gap(s) 190 by a spin-on process, aswould be known in the art.

FIG. 24 shows a cross-sectional perspective view of patterned and etchedtrench mask in a fin-gap and portion of a fin trench, in accordance withan embodiment of the present principles.

In one or more embodiments, portion(s) of the trench mask layer 220 maybe removed, while leaving one or more trench mask blocks 221 in one ormore fin-gaps 190 and/or one or more fin trench(es) 200. The trench maskblocks 221 may protect portions of pinch-off layer 210 and the substratesurface 105 in the fin-gaps 190 and/or fin trenches 200 from etchingduring formation of isolation region trenches.

In one or more embodiments, a soft mask may be formed and patterned onthe trench mask layer 220. Portions of the trench mask layer 220 may beremoved to expose portions of the pinch-off layer 210 on the substratesurface 105. The pinch-off layer 210 on the substrate surface 105 maysubsequently be removed to expose portions of the substrate surface 105at the bottom of one or more previously formed fin trench(es) 200 and/orfin-gap(s) 190. Removal of portions of the trench mask layer 220 canform one or more trench mask openings 225.

In various embodiments, the thickness of the pinch-off layer 210 on thesidewalls of the hardmask fin template segments 135, template linersegments 125, and vertical fin segments 115 defines the lateral distanceform a vertical fin segment 115 that a shallow trench isolation regionmay be formed.

FIG. 25 shows a partial cross-section and side view of the long axis ofvertical fin segments of FIG. 24 showing a plurality of trench maskblocks in fin trenches and fin-gaps, in accordance with an embodiment ofthe present principles.

A trench mask block 221 may fill a portion of a fin-gap 190 between twoadjacent sidewalls of the pinch-off layer 210 on the sidewalls of thehardmask fin template segments 135, template liner segments 125, andvertical fin segments 115. The trench mask block 221 may also fill aportion of one or more fin trench(es) 200. The trench mask block 221 mayextend above the top surface of the pinch-off layer 210.

FIG. 26 shows a side view of a plurality of trench mask openingsextending along the fin-gaps and trench mask blocks in the fin trenchbehind the pinch-off layer covered vertical fin segments, in accordancewith an embodiment of the present principles.

In one or more embodiments, the trench mask layer 220 may be removedfrom an entire fin-gap 190, and/or from an entire fin trench 200 wherean isolation region trench may be formed to separate bottomsource/drains and electrically isolate one or more vertical finFETs. Theincreased distance between vertical fin segments 115 across a fin gap190 may provide space for the formation of shallow trench isolationregions.

FIG. 27 shows a partial cross-section and side view of the long axis ofvertical fin segments of FIG. 24 showing an isolation region trenchextending into the substrate, and trench mask blocks shown in a fin gapbehind the pinch-off layer covered vertical fin segments, in accordancewith an embodiment of the present principles.

In one or more embodiments, the trench mask openings 225 may be extendedinto the substrate along at least a portion of a fin trench 200, where aportion of the substrate may be removed to form one or more isolationregion trenches 230 in the substrate 110. The substrate may be removedto form one or more isolation region trenches 230 between one or morehardmask fin template segments 135, template liner segments 125, andvertical fin segments 115 in the same column. The isolation regiontrenches 230 may form isolation regions (e.g., shallow trench isolationregions, deep trench isolation regions) in the substrate betweendevices. In various embodiments, the isolation region trenches 230 maybe formed by an anisotropic dry plasma etch (e.g., RIE) that does notetch the pinch off layer sidewalls. The etching of the trench may beselective for the substrate material, such that the pinch-off layer 210remains on the hardmask fin template segments 135 and vertical finsegments 115. In a non-limiting example, a silicon substrate may beselectively etched by RIE, while a silicon oxide pinch-off layer 210remains on the hardmask fin template segments 135, template linersegments 125, and vertical fin segments 115.

In one or more embodiments, a sidewall 231 of the isolation regiontrenches 230 may be offset from the vertical fin segment 115 by adistance, D₁, equal to or approximately equal to the thickness of thepinch-off layer 210, where the pinch-off layer may act as a hardmask toshield a portion of the substrate during formation of the isolationregion trench(es) 230. In various embodiments, the distance, D₁, may bein the range of about 0.1 nm to about 25 nm, or in the range of about 1nm to about 20 nm, or in the range of about 3 nm to about 10 nm, or inthe range of about 5 nm to about 25 nm, or in the range of about 10 nmto about 20 nm. In various embodiments, the thickness of the pinch-offlayer 210 may be the thickness of a conformal monolayer deposited byALD, and the distance, D₁, may be the thickness of the monolayer. Thethickness of the pinch-off layer may be controlled to a tolerance ofapproximately one monolayer by the ALD.

FIG. 28 shows a cross-sectional side view of a plurality of isolationregion trenches extending into the substrate with trench mask blocksshown in a fin gap behind the pinch-off layer covered vertical finsegments, in accordance with an embodiment of the present principles.

In one or more embodiments, the trench mask openings 225 may be extendedinto the substrate along at least a portion of a fin gap 190, where aportion of the substrate may be removed to form one or more isolationregion trenches 230 in the substrate 110. The portion(s) of thesubstrate 110 may be removed by a directional RIE to form the isolationregion trenches 230 in the substrate below the substrate surface 105 andthe level of the vertical fin segment 115, where a sidewall 231 of theisolation region trenches 230 may be offset from the vertical finsegment 115 by a distance, D₁, equal to or approximately equal to thethickness of the pinch-off layer 210 on the sidewalls of the hardmaskfin template segments 135, template liner segments 125, and vertical finsegments 115.

In various embodiments, the depth of the isolation region trench(es) 230may be in the range of about 10 nm to about 300 nm, or in the range ofabout 30 nm to about 200 nm, or in the range of about 40 nm to about 100nm. The depth of the isolation region trench(es) 230 may extend belowthe depth of a doped region forming a bottom source/drain.

In one or more embodiments, the isolation region trenches 230 may befilled with a dielectric material to form one or more shallow trenchisolation regions.

FIG. 29 shows a cross-sectional side view after removal of the trenchmask layer, in accordance with an embodiment of the present principles.

In one or more embodiments, the trench mask layer 220 may be removedafter formation of the isolation region trenches 230. The trench masklayer 220 may be removed by a RIE process to expose the pinch-off layer210 over hardmask fin template segments. In various embodiments, thetrench mask layer 220 may be an organic resist material that may beremoved by an oxygen ashing process.

FIG. 30 shows a cross-sectional side view of a dielectric fill layerover the pinch-off layer and in the trench mask openings and isolationregion trenches, in accordance with an embodiment of the presentprinciples.

In one or more embodiments, a dielectric fill layer 240 may be formed inthe trench mask openings 225 and isolation region trenches 230. Thedielectric fill layer 240 may be silicon dioxide (SiO₂). In variousembodiments, the dielectric fill layer 240 may be the same material asthe pinch-off layer 210, such that both the dielectric fill layer andthe pinch-off layer may be etched back in the same process.

FIG. 31 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, with a dielectric fill layer in the trench mask openings andisolation region trenches, in accordance with an embodiment of thepresent principles.

In one or more embodiments, the dielectric fill layer 240 may be formedin fin trench(es) 200 between one or more hardmask fin template segments135, template liner segments 125, and vertical fin segments 115 in thesame column.

The dielectric fill layer 240 may be an oxide formed, for example, by alow pressure CVD (LPCVD) process, flowable CVD (FCVD) process, enhancedHigh Aspect Ratio Process (eHARP) process, High Aspect Ratio Process(HARP) process, high density plasma (HDP) process, or a combinationthereof. The dielectric fill layer 240 may extend above the top surfaceof the hardmask fin template segments 135, and a CMP may be used toreduce the height of the dielectric fill layer 240 and provide a flatuniform surface. A heat treatment (e.g., annealing, etc.) may be used todensify the formed oxide.

FIG. 32 shows a cross-sectional side view of a plurality offree-standing hardmask fin template segments, template liner segments,and vertical fin segments, after removal of the pinch-off layer and aportion of the dielectric fill layer, in accordance with an embodimentof the present principles.

In one or more embodiments, portion of the dielectric fill layer 240 maybe removed, from the trench mask openings 225, where a portion of thedielectric fill layer 240 may remain in the isolation region trenches230 to form shallow trench isolation regions 245 in the isolation regiontrenches 230 of the fin-gap(s) 190. The shallow trench isolation regions245 may separate doped regions 250 into separate bottom source/drainsfor separate finFETs.

FIG. 33 shows a cross-sectional side view of the long axis of hardmaskfin template segments, template liner segments, and vertical finsegments, after removal of the pinch-off layer and a portion of thedielectric fill layer, in accordance with an embodiment of the presentprinciples.

In one or more embodiments, dielectric fill layer 240 may be formed inthe isolation region trenches 230 of the fin trench(es) 200, and portionof the dielectric fill layer 240 may be removed to form shallow trenchisolation regions 245.

In one or more embodiments, the dielectric fill layer 240 and pinch-offlayer 210 may be etched back to the surface of the substrate to leavethe shallow trench isolation (STI) regions 245 in the substrate 110between the vertical fin segments 115.

FIG. 34 shows a cross-sectional side view of a plurality offree-standing vertical fin segments, and self-aligned shallow trenchisolation regions, in accordance with an embodiment of the presentprinciples.

In one or more embodiments, the shallow trench isolation regions 245 areself-aligned with the vertical fin segments 115 due to the control ofthe positioning of the isolation region trenches 230 by the thickness ofthe pinch-off layer 210 on the sidewalls and/or endwalls of the verticalfins. Since the positioning of the isolation region trenches 230 is notcontrolled by the lateral accuracy of a masking process, the isolationregion trench positioning can be controlled to a tolerance of one ormore monolayers through an ALD process forming the pinch-off layer 210.

In one or more embodiments, the doped regions 250 in the substrate 110below the vertical fin(s) may form bottom source/drains for a finFET,where the hallow trench isolation regions 245 define a perimeter of thebottom source/drain for one or more vertical fin segments 115. Thebottom source/drain(s) may be formed by in-situ doping or ex-situdoping.

A non-limiting example of a method of forming a vertical fin fieldeffect transistor (vertical finFET) with a self-aligned shallow trenchisolation region, includes forming one or more vertical fins on asubstrate; forming a filler layer in the gaps between each of the one ormore vertical fins; forming and patterning a fin-cut mask layer on atleast a portion of the surface of the filler layer and vertical fins toform a plurality of fin-cut mask blocks; removing portions of the fillerlayer and vertical fins not covered by the fin-cut mask blocks to formone or more vertical fin segments; forming a pinch-off layer on the oneor more vertical fin segments, wherein the pinch-off layer has athickness on the sidewalls of the one or more vertical fin segments;forming a trench mask layer on predetermined portions the pinch-offlayer; removing portions of the pinch-off layer not covered by thetrench mask layer, where the removed portions of the pinch-off layerexposes underlying portions of the substrate; and removing at least aportion of the substrate to form one or more isolation region trenches,where the distance of the sidewall of one of the one or more isolationregion trenches to an adjacent vertical fin segment is determined by thethickness of the pinch-off layer.

It is to be understood that the present invention is described in termsof a given illustrative architecture; however, other architectures,structures, substrate materials and process features and steps may bevaried within the scope of the present invention.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments may include a design for an integrated circuitchip, which may be created in a graphical computer programming language,and stored in a computer storage medium (such as a disk, tape, physicalhard drive, or virtual hard drive such as in a storage access network).If the designer does not fabricate chips or the photolithographic masksused to fabricate chips, the designer may transmit the resulting designby physical means (e.g., by providing a copy of the storage mediumstoring the design) or electronically (e.g., through the Internet) tosuch entities, directly or indirectly. The stored design is thenconverted into the appropriate format (e.g., GDSII) for the fabricationof photolithographic masks, which typically include multiple copies ofthe chip design in question that are to be formed on a wafer. Thephotolithographic masks are utilized to define areas of the wafer(and/or the layers thereon) to be etched or otherwise processed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element's or feature's relationship to another element(s)or feature(s) as illustrated in the FIGs. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the FIGs. For example, if the device in theFIGs. is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” cab encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations), and the spatially relativedescriptors used herein may be interpreted accordingly. In addition, itwill also be understood that when a layer is referred to as being“between” two layers, it can be the only layer between the two layers,or one or more intervening layers may also be present.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Thus, a first element discussed belowcould be termed a second element without departing from the scope of thepresent concept.

While exemplary embodiments have been shown for a particular device, itshould be understood that a plurality of such devices may be arrangedand/or fabricated on a substrate to form integrated devices that may beintegrated onto a substrate, for example through very large scaleintegration to produce complex devices such a central processing units(CPUs) and application specific integrated circuits (ASICs). The presentembodiments may be part of a device or circuit, and the circuits asdescribed herein may be part of a design for an integrated circuit chip.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A method of forming a vertical fin field effecttransistor (vertical finFET) with a self-aligned shallow trenchisolation region, comprising: forming a first vertical fin, a secondvertical fin, and a third vertical fin on a substrate surface, whereinthree vertical fins are adjacent, and the second vertical fin is betweenthe first vertical fin and the third vertical fin; removing the secondvertical fin to form a fin gap; forming a pinch-off layer on the firstvertical fin, third vertical fin, and the substrate surface between thefirst vertical fin and third vertical fin, wherein the pinch-off layerhas a thickness of less than half the distance between the firstvertical fin and the third vertical fin, so a portion of the pinch-offlayer on the substrate surface is exposed; removing the exposed portionof the pinch-off layer to expose the substrate; and removing at least aportion of the substrate to form an isolation region trench, wherein thedistance of a sidewall of the isolation region trench to an adjacentvertical fin segment is determined by the thickness of the pinch-offlayer.
 2. The method of claim 1, further comprising filling the one ormore isolation region trenches with a dielectric fill layer to form oneor more shallow trench isolation regions.
 3. The method of claim 1,wherein the pinch-off layer is formed on the first vertical fin, thirdvertical fin, and the substrate surface by atomic layer deposition(ALD).
 4. The method of claim 3, wherein the pinch-off layer has athickness in the range of about 3 nm to about 10 nm.
 5. The method ofclaim 4, wherein the thickness of the pinch-off layer is controlled toapproximately one monolayer by the ALD.
 6. The method of claim 4,wherein pinch-off layer is silicon oxide.
 7. The method of claim 1,further comprising removing a portion of each of the first and thirdvertical fins to form two vertical fin segments from each of the firstand third vertical fins before forming the pinch-off layer.
 8. Themethod of claim 7, further comprising removing an exposed portion of thepinch-off layer and at least a portion of the substrate to form anisolation region trench between the two vertical fin segments.
 9. Amethod of forming a vertical fin field effect transistor (verticalfinFET) with a self-aligned shallow trench isolation region, comprising:forming a plurality of vertical fin segments on a substrate; forming apinch-off layer on the plurality of vertical fin segments and thesubstrate, wherein the pinch-off layer has a thickness on the sidewallsand endwalls of each of the plurality of vertical fin segments, andwherein a portion of the pinch-off layer between at least two of theplurality of vertical fin segments is exposed; removing the exposedportion of the pinch-off layer to expose an underlying portion of thesubstrate; and removing at least a portion of the substrate to form anisolation region trench, where a distance of a sidewall of the isolationregion trench to an adjacent vertical fin segment is determined by thethickness of the pinch-off layer.
 10. The method of claim 9, furthercomprising filling the isolation region trench with a dielectric filllayer to form a shallow trench isolation region between two vertical finsegments.
 11. The method of claim 10, wherein dielectric fill layer issilicon dioxide (SiO₂).
 12. The method of claim 10, wherein thepinch-off layer is formed on the plurality of vertical fin segments byatomic layer deposition (ALD).
 13. The method of claim 10, wherein thepinch-off layer has a thickness in the range of about 0.1 nm to about 25nm.
 14. The method of claim 10, wherein the isolation region trench hasa depth in the range of about 5 nm to about 200 nm.
 15. The method ofclaim 10, wherein the pinch-off layer is SiO₂, SiN, SiON, or TiN.
 16. Amethod of forming a vertical fin field effect transistor (verticalfinFET) with a self-aligned shallow trench isolation region, comprising:forming a plurality of vertical fin segments on a substrate; forming apinch-off layer on the plurality of vertical fin segments and thesubstrate, wherein the pinch-off layer has a thickness in the range ofabout 0.1 nm to about 25 nm on the sidewalls and endwalls of each of theplurality of vertical fin segments, and wherein a portion of thepinch-off layer on the substrate between at least two of the pluralityof vertical fin segments is exposed; removing the exposed portion of thepinch-off layer to expose an underlying portion of the substrate; andremoving at least a portion of the substrate to form an isolation regiontrench, where a distance of a sidewall of the isolation region trench toan adjacent vertical fin segment is determined by the thickness of thepinch-off layer.
 17. The method of claim 16, wherein the pinch-off layeris SiO₂, SiN, SiON, or TiN.
 18. The semiconductor device structure ofclaim 17, wherein the pinch-off layer is formed on the one or morevertical fin segments by atomic layer deposition (ALD).
 19. The methodof claim 17, wherein the isolation region trench has a depth in therange of about 5 nm to about 200 nm.
 20. The semiconductor devicestructure of claim 19, wherein the isolation region trench passesthrough a doped region to form separate bottom source/drains.